1. Field of the Invention
The present invention relates to a method of forming an organic semiconductor thin film and a method of manufacturing a thin-film semiconductor device and, in particular, relates to a method of forming an organic semiconductor thin film applicable to printing techniques and a method of manufacturing a thin-film semiconductor device using that method of formation.
2. Description of the Related Art
Recently considerable interest has been shown in thin-film transistors using organic semiconductor thin films as an active layer, that is to say, organic thin-film transistors. Organic thin-film transistors can be applied to printing techniques for pattern formation of an organic semiconductor thin film forming an active layer. Consequently in addition to costs savings, pattern formation is enabled on flexible substrates such as plastics which do not have heat-resistant properties.
Pattern formation on organic semiconductor thin films using printing method is performed as follows. Firstly water-resistant polydimethylsiloxane (PDMS) is used to form a tabular stamp plate provided with an indented pattern on a surface thereof. Then a spin coating method is used to coat an organic semiconductor ink on the entire surface (water-resistant surface) of the stamp plate. For example, the organic semiconductor ink is produced by dissolving an organic semiconductor material formed from poly(3-hexylthiophene (P3HT)) in a solvent formed from chloroform. After the organic semiconductor ink is dried on the stamp plate to form an organic semiconductor thin film, the formation face of the organic semiconductor thin film on the stamp plate is pressed onto a device substrate forming the thin-film transistor. In this manner, the organic semiconductor thin film section formed on the protruding pattern of the stamp plate can be closely attached to the substrate surface of the device substrate. Then the stamp plate is peeled from the device substrate in order to transcribe the organic semiconductor thin film pattern from the protruding pattern of the water-resistant stamp plate to the device substrate. (For example refer to Japanese Patent Laid-Open No. 2007-67390).